The rapid de-excitation system for synchronous machines with indirect excitation described in patent ES2325729 successfully improves dynamic response and safety when it comes to de-exciting the machine, which means that in the event of an internal short circuit, the machine would be damaged to a much lesser extent.
During usual operation, the manoeuvre element in the de-excitation system should be connected and current should barely circulate through the de-excitation resistor. In the event of this system operating poorly, the manoeuvre element would not drive, thus meaning the excitation current must circulate through the de-excitation resistor. In this case, the machine may be damaged as a result of overheating in the de-excitation resistor.
Furthermore, in the event of poor operation, in order for a certain current to continue circulating through the excitation winding of the main generator, the excitation current of the excitation winding of the exciter must be increased.
As such, a monitoring system capable of determining whether or not the rapid de-excitation system is operating correctly becomes necessary, i.e. a system capable of determining whether or not the manoeuvre element drives during normal operation.